A known effective class of detergent-dispersants for lubricating oils in the prior art are the N-substituted alkenyl succinimides which can be characterized by the formula: ##STR1## where R is alkenyl (monovalent, monoolefinic hydrocarbon) having a carbon chain length of between about 30 and 300 and D is an amine group consisting of alkylene amino and polyalkylene polyamine radicals. These prior nitrogenous dispersants are prepared by reacting polyalkene or halopolyalkene to form alkenyl substituted succinic anhydride followed by the conversion of the alkenyl succinic anhydride to the above described succinimide via the reaction of the anhydride with alkylene polyamine.
For a given weight, there appears to be a direct relationship between the nitrogen content of the ashless dispersants derived from maleic anhydride derivatives and polyalkylene polyamines in respect to detergent-dispersant activity in lubricating oils, the greater the nitrogen content the more effective the material as a detergent-dispersant. These maleic anhydride alkylene polyamine derivatives, although often characterized in terms of succinimide structures, are in essence a complex mixture of compounds some of which may include succinimides, polycyclic nitrogen containing ring compounds and aliphatic amino substituted polyalkenes. The exact character of the complex nitrogenous dispersant and the amount of effective nitrogen which can be incorporated in the nitrogen dispersant for a given weight is determined by the method of manufacture.
There is a continuing need for lubricant additives having an increased detergent-dispersancy, and therefore, nitrogenous ashless dispersants of increasing nitrogen content are in continual demand.
Accordingly, one object of the invention is to provide an intermediate product and method of manufacture from which nitrogenous detergent-dispersants for lube oils of increased nitrogen content can be produced with resultant increased detergent-dispersancy.
Another object of the invention is to provide nitrogenous dispersants of an increased nitrogen content, i.e., of increased detergent-dispersant effectiveness and lubricating oil compositions thereof.